1. Field of the Invention
The present invention relates to a collective element of quantum boxes.
2. Background of the Invention
Recently, in the field of quantum wave electronics, attention has been paid to the so-called quantum box which has an extremely small structure with a cross sectional dimension being approximately the same as a de Broglie wavelength of an electron. People have been very interested in the quantum effect which is shown by a zero dimensional electron kept in this quantum box.
The collective element of quantum boxes is made of a plurality of these quantum boxes combined with each other. The element is intended to perform data processing with a varying distribution of electrons by causing a tunneling (in the meaning of quantum mechanics) of an electron (e.sup.-) between the quantum boxes, as shown in FIG. 10. In the drawing, E.sub.CB and E.sub.CW respectively show the energies at lower ends of conduction bands for a barrier layer and a well layer.
The following steps have been considered to perform the data processing. First, by providing an incident ray into the collective element of the quantum boxes, the data entry is performed. An electron and hole pair are generated by the incident ray. The tunneling is caused only for the electron.
However, when the quantum box is made of the superlattice of so-called type I such as the hetero junction of AlGaAs/GaAs as shown in FIG. 11, for example, an electron and hole pair generated in the quantum box by the incident ray could be more stabilized in the quantum box, rather than in the barrier layer. Therefore, the probability becomes large for both the electron and the hole to stay in the quantum box and re-couple to each other and then disappear. It becomes very difficult for only the electron to be tunneled and conducted between the quantum boxes.